1. Field of the Invention
The present invention relates to a machine tool having a spindle, a tool changer for conveying tool holders between a magazine position and a spindle position on the spindle, and a linear stroke mechanism for conveying a tool holder between the spindle position and a working position in a tool receptacle of the spindle.
2. Description of Related Prior Art
A machine tool of this kind is known from DE 44 21 385 A1.
In the known machine tool, the spindle is rotatably mounted in a spindle tube. The tool changer comprises two gripper arms for transporting the tool holders between the magazine position and the spindle position beneath the tool receptacle. A holding mechanism which carries the tool changer and serves to convey the respective tool holder from the spindle position into its working position in the tool receptacle is mounted on the spindle tube, displaceable longitudinally in a linear stroke motion. The holding mechanism is mounted rotatably on the spindle tube, about its longitudinal axis, in such a way that the gripper arms have a common transfer position with respect to the tool magazine.
A hydraulic piston-cylinder unit is provided to drive each of the two gripper arms. A further piston-cylinder unit is also provided for the rotary and linear stroke motions of the holding mechanism. A rotary mechanism ensures that under certain conditions, the holding mechanism is forced to rotate during the linear stroke motion.
Tool changes can be performed rapidly with this machine tool, but the design complexity is relatively high.